1. Field of the Invention
The field of the invention relates to air purifiers, particularly to portable air purifiers including HEPA filters.
2. Brief Description of the Prior Art
Portable air purifiers for removing airborne particles are used in many homes and offices. Such purifiers often include a fine particle high efficiency particulate air (HEPA) filter. In addition to a HEPA filter, some purifiers include a carbon filter to remove odors. The carbon may be incorporated within a fibrous matrix. A filter for trapping relatively large particles may also be found in portable air purifiers. In operation, one or more fans cause air to be drawn through the filter(s) and emitted through an outlet.
HEPA filters have gained increasing acceptance for use in purifiers directed to consumers as they remove 99.97% of particles having a size equal to or greater than 0.3 microns. In order to take full advantage of a HEPA filter or any other type of filter used in an air purifier, it is important to ensure that substantially all of the air emitted by the air purifier has indeed first passed through the filter(s) provided in the purifier. Where a filter includes both a HEPA component and filter component, the lifespan of the filter is generally dependent upon the carbon component. This is because the trapping capacity of the carbon component is generally exhausted prior to that of the HEPA component.
As the filter(s) employed in air purifiers require replacement when spent, the ability to easily remove and replace the filter(s) is important. A replaced filter must be properly installed if it is to function properly. Disposable filter assemblies have accordingly been designed to facilitate user convenience.
Currently portable air purifiers are manufactured in various sizes with different capacities to suit a consumer's particular needs. The larger capacity air purifiers generally require larger sized filters. This generally requires retailers to stock a plurality of different size filter elements to satisfy the demands of all consumers. Replacement HEPA filter elements are traditionally bulky and expensive inventory for retailers to maintain. The retailer must stock the replacement filters for every air purifier that is sold, but the filters generally do not need replacement very frequently. The retailers that carry air purifiers are required out of necessity to offer a line of different size units that are expensive to purchase, do not turn over very often, and take up a lot of shelf space. In addition, to exacerbate the problem it has been found that by the time the consumer needs to replace the filter element, the inventory is old and looks beat up.
A number of patents have issued which disclose air purifiers including HEPA filters, carbon filters, and/or other filters. U.S. Pat. Nos. 3,928,008; 4,378,983; 4,521,234; 4,629,482; 4,737,173; 4,778,496; 5,078,764; 5,102,435; 5,131,932; 5,230,723; 5,259,854; 5,290,330; 5,512,086; and 5,893,939 disclose air purifiers of various constructions. The disclosure of the U.S. Pat. No. 5,893,939 patent is incorporated herein by reference.